text: Octahedral clusters of tin(II) have been observed in several solid state compounds. The reaction of tin(II) salts with an aqueous base leads to the formation of tin(II) oxyhydroxide (SnO(OH)), the structure of which comprises discrete SnO(OH) clusters. In SnO(OH) clusters, the six tin atoms form an octahedral array with alternate faces of the octahedron occupied by an oxide or hydroxide moiety, each bonded in a µ-binding mode to three tin atoms. Crystal structures have been reported for compounds with the formula SnO(OR), where R is an alkoxide such as a methyl or ethyl group.
  Recently, it was demonstrated that anionic tin(II) clusters [SnO] may form the close packed arrays as in the case of α-SnSiO, which adopts the zinc blende structure, comprising a face-centred-cubic array of [SnO] clusters with Si occupying half of the tetrahedral holes. A polymorph, β-SnSiO, has been identified as a product of pewter corrosion in aqueous conditions, and is a structural analogue of wurtzite.